i've found more success by having an outside healer on my team. My pally has been severely lacking on points because of it, but thats just how it rolls. There are some things i've found that work rather well with two healer teams, as long as they're not 1800 rated when you're like 1400... you're gonna lose those matches regardless of two heals or not.

what i start out with is a macro that deathgrips EVERYONE into range, fires off two howling blasts and then hungering cold. *(ie i have a macro for each dk that does /cast @arena1-4 deathgrip, and then just target arena 5 and focus fire on him)... this usually causes two things to happen, their team will instinctively pop all defensive cooldowns or trinkets, pop hungering cold again and then obliterate spam and blood strike spam, pop runic empowerment and obliterate 3 times on each dk.

IF you can "surprise" a group like this then you're going to down someone almost assuredly. The /focus on a healer and round robin on strangulate is a good touch as well, tho i haven't implemented it yet, i just have strangulate on my T key on round robin and use it to burst down heals or stop mages from being pesky.

IMO hire a healer, get your points for a couple weeks on your dks and buy the 359 weapons(axe mace sword, depending on race and preference) I mainly work the pally in when one of my 5 other healers aren't around to play. I usually win close to same rated teams, but anything thats mmr 1650 + wrecks me(ie the opponents are usually a good 200 to 400 rating higher than me IF they win, anything like rated or lower loses harshly to me lol). I've got about 3100 resil on my dks too, so they stay alive a bit longer.

One thing you can learn to do is to manage defensive cooldowns better, and wear out their healers mana by focusing on a hard to kill target. Watch them closely and when they get low grip BOTH healers into the kill zone and go for the burst with a mix of howling blast and obliterate , using runic empowerment then, to really mess them up. If you can keep their DPS on the defensive and put out LOTZ of dmg so that the healers HAVE to pressure heal, then they're going to burn out on mana quick(lol thats a relative term but you get the idea) then just try to grip and burst. going against two healers is going to be all about the outlast the mana and then cc/burst. Target swapping when someone gets low is kinda win as well once they get low on mana. Make them MAKE choices, and react to you, vs you just smacking against the wall.

Liek the others have said before me here, you really should get some weapons that was MY biggest wall, and once i got my 359 axes i started really rolling over teams. Stack strength /resil and keep that spell pen capped and you should be seeing better numbers soon <3 =)